JP3970173B2 - Method for producing pulp molded article - Google Patents

Description

【００９４】
表１に示すように、実施例１の容器は、成形性、断熱性、強度の何れにも優れているのに対し、比較例１では、内層の抄造後に抄造型を合体成型用の雌型に突き合わせるときに、抄造体の先端部分のパルプの盛り上がりが雌型の内面と接触することとなり、内層に破断が生じるため、成形性が悪く、強度も測定できなかった。また、段差近傍部の密度及び肉厚部の密度及び肉厚部の密度を他の部位より小さくしたものは、スタックしたときにブロッキングが発生した。また、真空成形にしてフィルムをラミネートした場合、スタック部に割れが発生した。
【００９５】
【発明の効果】
本発明によれば、軽量で成形性及び断熱性に優れ且つ高い強度を有し、廃棄性にも優れるパルプモールド成形体の製造方法及びパルプモールド成形容器が提供される。
【図面の簡単な説明】
【図１】本発明のパルプモールド成形容器を食品容器に適用した一実施形態を模式的に示した図であり、（ａ）は半断面図、（ｂ）は（ａ）の要部拡大図である。
【図２】本発明のパルプモールド成形体の製造方法を食品容器の製造に適用した一実施形態の工程を模式的に示す図であり、（ａ）は内層容器用抄造体の抄造工程を示す図、（ｂ）は、外層容器用抄造体の抄造工程を示す図、（ｃ）は外層容器用抄造体の脱水・乾燥成形工程を示す図、（ｄ）内層容器用抄造体と外層容器用抄造体の合体工程を示す図、（ｅ）は食品容器の乾燥成形工程を示す図である。
【符号の説明】
１ 食品容器
２ 内層容器（パルプモールド成形容器）
２０ フランジ部
２１ 胴部
２２ スタック用段差（段差）
２３ 肉薄部
２３ａ 近傍部
２４ｂ 他の部分
２４ 肉厚部
３ 外層容器
３０ フランジ部
３１ 胴部
２’、３’ 抄造体
１２、１３ 抄造型
１２０、１３０ 抄造部
１２３ 細抄造部
１４ 雌型
１４０ 凹部
１５ 雄型
１５０ 成形部
１５１ 細成形部
１６ 雌型
１６０ 凹部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a pulp mold product and a pulp mold container, and in particular, the thickness changes from a thin part to a thick part through a step, and the density of the vicinity of the step in the thin part is In addition, the present invention relates to a method for producing a pulp mold molded body that is higher than the density of other portions of the thin portion in the thin portion and equal to or higher than the density of the thick portion, and a pulp mold container.
[0002]
[Prior art and problems to be solved by the invention]
Paper containers made of paperboard are mainly used for food containers such as instant cup noodles. Such a food container may require a step for stacking or a hot water line on the inner surface. For this reason, it is necessary to provide in the trunk | drum the part from which a thickness changes from a thin part to a thick part through a level | step difference (for example, refer patent document 1).
[0003]
[Patent Document 1]
Utility Model Registration No. 3065471
[0004]
The present inventors have already filed a patent application for a manufacturing technique of a container in which the thickness of the body part changes from a thin part to a thick part through a step as described above by using a pulp mold without using paperboard (for example, (Japanese Patent Application No. 2001-128387).
[0005]
By the way, when the disposal property and productivity of a container are considered, the container is comprised with fewer components, and the container which is lightweight, is excellent in a moldability and heat insulation property, and has high intensity | strength is desired.
[0006]
Accordingly, an object of the present invention is to provide a method for producing a pulp molded article and a pulp mold molded container that are lightweight, excellent in moldability and heat insulation, have high strength, and are excellent in discardability.
[0007]
[Means for Solving the Problems]
According to the present invention described below, the present inventors provide a pulp mold molded body that can achieve the above-mentioned object in which the thickness changes from a thin part to a thick part through a step in a single layer mainly composed of pulp fibers. It was found that it can be manufactured.
[0008]
In the present invention, the thickness changes from the thin part to the thick part through the step, and the density of the vicinity of the step in the thin part is higher than the density of the other part in the vicinity of the thin part. And it is a manufacturing method of the pulp mold fabrication object which is more than the density of this thick part, and the basis weight of the part corresponding to the neighborhood part of the level difference in the thin part and the thick part is the other part of the thin part A method for producing a pulp mold molded body, wherein a papermaking body is dehydrated and molded so as to be higher than a basis weight of a portion corresponding to the portion, and the papermaking body is dry-molded while being pressed in a molding die having a cavity corresponding to the step. It is to provide.
[0009]
In the present invention, the thickness is changed from the thin portion to the thick portion through the stacking step, and the density of the vicinity of the step in the thin portion is equal to that of the other portion in the thin portion. A pulp molded container having a density higher than the density and equal to or higher than the density of the thick part is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below based on preferred embodiments with reference to the drawings.
[0011]
FIG. 1 schematically shows an embodiment in which the pulp molded container of the present invention is applied to an inner layer container of a food container such as instant cup noodles. In FIG. 1, reference numeral 1 denotes a food container, 2 denotes an inner layer container, and 3 denotes an outer layer container.
[0012]
As shown in FIG. 1, the food container 1 is a bottomed cylindrical container having a two-layer structure in which an outer layer container 3 having a flange portion 30 is combined with an outer side of an inner layer container 2 having a flange portion 20.
[0013]
The inner layer container 2 has a stacking step 22 in the body portion 21. The trunk portion 21 changes in thickness from the thin portion 23 to the thick portion 24 via the stacking step 22, and the density ρ of the vicinity 23 a of the stacking step 22 in the thin portion 23. _23a Is the density ρ of the other portion 23b of the thin portion 23 _23b And the density ρ of the thick part 24 _{twenty four} It is provided as described above. Here, the thin portion 23 refers to a portion of the trunk portion 21 from the stacking step 22 to the flange portion, and the thick portion 24 refers to a portion of the trunk portion 21 from the stacking step 22 to the bottom surface portion 25. In this specification, the term “density” means bulk density.
[0014]
In the food container 1 of the present embodiment, the density ρ of the vicinity 23a. _23a And the density ρ of the other portion 23b _23b The difference from 0.1 to 0.4 g / cm ^Three , Especially 0.15-0.3g / cm ^Three It is preferable that If the density difference is too small, the heat insulating property and light weight are impaired when the density is high, and the strength is impaired when the density is low. If the density difference is too large, the heat insulating property and thin wall thickness of the thick part are impaired. The strength of the part will be impaired. Here, the vicinity 23a refers to a portion from 0 to 10 mm from the stack step 22, and the density refers to the density of the portion. The other portion 23b refers to a portion separated from the stack step 22 by more than 10 mm, and the density refers to the density of the portion.
[0015]
Density ρ of the thick part 24 _{twenty four} Is the density ρ of the other portion 23b of the thin portion 23 in terms of increasing the strength. _23b The above is preferable. In addition, the flange part of an opening part is remove | excluded from the said part.
[0016]
In the food container 1 of the present embodiment, the density ρ of the vicinity 23a. _23a And the density ρ of the thick part 24 _{twenty four} The difference from 0.1 to 0.4 g / cm ^Three , Especially 0.15-0.3g / cm ^Three It is preferable that If the density difference is too small, the heat insulating property and light weight are impaired when the density is high, and the strength is impaired when the density is low. If the density difference is too large, the heat insulating property and thin wall thickness of the thick part are impaired. The strength of the part will be impaired.
[0017]
In the food container 1 of the present embodiment, the density ρ of the vicinity 23a. _23a Is 0.15 to 0.7 g / cm ^Three , Especially 0.25-0.5 g / cm ^Three It is preferable that
[0018]
In the food container 1 of the present embodiment, the density ρ of the other portion 23b. _23b Is 0.05 to 0.5 g / cm ^Three In particular, 0.1 to 0.4 g / cm ^Three It is preferable that
[0019]
In the food container 1 of the present embodiment, the density ρ of the thick portion 24 _{twenty four} Is 0.05 to 0.5 g / cm ^Three , Especially 0.15-0.4 g / cm ^Three It is preferable that
[0020]
In the food container 1 of the present embodiment, the density of the entire body portion 21 of the inner layer container 2 is 0.1 to 0.6 g / cm. ^Three , Especially 0.15-0.45 g / cm ^Three It is preferable that
[0021]
In the food container 1 of the present embodiment, the density of the flange portion is 0.1 to 1.2 g / cm. ^Three , Especially 0.2-0.8g / cm ^Three It is preferable that
Further, the density of the bottom is 0.1 to 1.2 g / cm. ^Three , Especially 0.2-0.8g / cm ^Three It is preferable that
[0022]
In the food container 1 of the present embodiment, the difference in thickness between the thin portion 23 and the thick portion 24 is more preferably 0.5 to 4 mm, and particularly preferably 0.7 to 3 mm. If the difference in thickness is too small, a stacking function for stacking steps cannot be obtained. If the difference in thickness is too large, the weight of the container becomes unnecessarily heavy, and it takes time to dry the stack steps, resulting in a long manufacturing cycle.
[0023]
In the food container 1 of this embodiment, it is preferable that the thickness of the thin portion 23 is 0.5 to 4 mm, particularly 0.7 to 3 mm.
[0024]
In the food container 1 of this embodiment, the thickness of the thick portion 24 is preferably 1 to 6 mm, particularly 1.4 to 4.5 mm.
[0025]
In the food container 1 of this embodiment, it is preferable that the flange portion has a thickness of 1 to 5 mm, particularly 2 to 4 mm.
Moreover, it is preferable that the thickness of a bottom part is 0.5-4 mm, especially 0.7-3 mm.
[0026]
In the food container 1 of this embodiment, it is preferable that the inner layer container 2 contains bulky treated pulp as a pulp component. The amount of the bulky treated pulp contained in the inner layer container 2 is preferably 10 to 90 wt%, more preferably 20 to 70 wt% in the pulp components constituting the inner layer container 2. If the blending amount of the bulky treated pulp in the pulp component is less than 10 wt%, the bulkiness is lowered, the heat insulating property is lowered, the shape transferability is insufficient, the surface property is inferior, and a desired step can be formed. There is a risk of disappearing. If it exceeds 90 wt%, the gripping strength or buckling strength of the container may be reduced, the stack strength of the inner layer may be reduced, or the container may be crushed or damaged when a film layer is provided on the inner surface by vacuum forming.
Here, the bulky treated pulp used in the inner layer container 2 refers to a pulp fiber that has been curled or hydrophobized by a bulky treatment such as a cross-linking treatment or a mercerization treatment, or the rigidity of the fiber itself has been improved. As the cross-linked pulp, commercially available curd fibers (for example, “HBA” manufactured by U.S. Warehauser), and as the mercerized pulp, commercially available mercerized pulp (for example, “POROSAUIE”, “ULTRANIER,” manufactured by Rayonnia) are used. "SULFATE").
[0027]
The cross-linked pulp and mercerized pulp can be used alone or in combination of two or more.
For example, the mercerized pulp can be used by mixing with the crosslinked pulp. In this case, it is preferable to add 20 to 500%, particularly 50 to 300% by weight with respect to the cross-linked pulp. If the ratio of mercerized pulp to the crosslinked pulp is too high, the mercerized pulp is inferior in bulk compared to the crosslinked pulp, so that the strength of the inner layer container and the moldability (transferability) of the inner surface of the inner layer container are improved. On the other hand, if the amount is too small, flocs of pulp fibers increase and papermaking unevenness is likely to occur.
[0028]
When the cross-linked pulp is used among the bulky treated pulp, it is preferable that the wet curled factor is 0.1 to 1.0, particularly 0.2 to 0.6. If the wet curled factor is too low, the desired bulkiness may not be obtained. If the wet curled factor is too high, the dispersibility in the raw material slurry is deteriorated, unevenness in papermaking occurs and uneven thickness is produced in the resulting molded product, which may reduce the strength and surface properties of the molded product. Here, wet curd factor means that after pulp fibers are immersed in pure water at room temperature and using FQA (Fiber Quality Analyzer), the number of measurement is 1000 or more and the measurement range is 0.5 to 10 mm ((L _A / L _B ) -1) is a value determined by the arithmetic average, and is a numerical value indicating the degree of fiber curving. However, L _A Is the actual pulp fiber length, L _B Is the maximum dimension of the rectangle surrounding the bent pulp fiber.
[0029]
The inner layer container 2 can contain, as the pulp component, pulp fibers that are not subjected to bulky treatment in addition to the bulky treated pulp. The pulp fiber is preferably contained in the pulp component in an amount of 10 to 90 wt%, particularly 30 to 80 wt%. When the pulp fiber is less than 10 wt%, the strength of the flange portion and the container is reduced and a lot of paper dust is generated, and the added amount of the binder is increased in order to obtain strength and prevent paper dust. If it exceeds 90 wt%, the proportion of the bulky treated pulp decreases, and the bulkiness is lowered, and the cushioning property of the flange portion and the heat insulating property of the container may be lowered. Examples of the pulp fiber include unbleached or bleached kraft pulp, sulfite pulp, alkali pulp, ground pulp, or thermomechanical pulp of softwood or hardwood. These pulp fibers can be used alone or in admixture of two or more at an appropriate ratio. In particular, by mixing two or more kinds, pulp fibers having various fiber length distributions can be prepared.
[0030]
The pulp fiber preferably has a CSF (Canadian Standard Freeness) of 200 to 700 ml, particularly 300 to 600 ml. If the CSF is too low, the drainage may be reduced, and the paper making time and drying time may be prolonged. If the CSF is too high, paper making unevenness will be remarkable, resulting in uneven thickness in the resulting molded product, and surface properties of the molded product. May decrease.
[0031]
The average fiber length of the pulp fibers not subjected to bulky treatment is preferably 0.4 to 5 mm, particularly preferably 0.5 to 3 mm. When the average fiber length of the pulp fiber is too short, the entanglement with the bulky treated pulp is reduced, so that the strength of the obtained molded product is lowered and a large amount of paper powder is easily generated. On the contrary, if the average fiber length is too long, the entanglement with the bulky treated pulp becomes too large, so that the flocs become large and papermaking unevenness is likely to occur, resulting in uneven thickness in the obtained molded product, and the surface property also decreases. There is a case.
[0032]
Any of the pulp fibers of wood pulp and non-wood pulp can be used for the bulky treated pulp and the pulp fiber used as the pulp component of the inner layer container 2. Further, any pulp fiber of virgin pulp and waste paper pulp can be used. These pulp fibers can be used alone or in admixture of two or more at an appropriate ratio.
[0033]
The inner layer container 2 may contain 0.2 to 10 wt% of a bulking agent. By including a bulking agent within these ranges, bulkiness can be obtained more stably.
Examples of the bulking agent include “KB115” and “KB85” manufactured by Kao Corporation, and among these, “KB115” is preferable because it can suppress bulkiness and obtain bulkiness. .
[0034]
The inner layer container 2 may contain additives for the inner layer such as a dispersant, a pigment, a fungicide, a sizing agent, a paper strength enhancer, a water resistance agent, and an adhesive in an appropriate ratio as necessary.
[0035]
In the food container 1 of the present embodiment, the outer layer container 3 has a body portion 31 having a substantially uniform thickness and a substantially uniform density.
[0036]
In the food container 1 of this embodiment, it is preferable that the thickness of the trunk | drum 31 of the said outer layer container 3 is 0.2-1.0 mm, especially 0.3-0.8 mm.
[0037]
In the food container 1 of the present embodiment, the density of the entire body 31 in the outer layer container 3 is 0.5 to 1.5 g / cm. ^Three , Especially 0.6-1.2g / cm ^Three It is preferable that If the density is too high, the weight will become unnecessarily heavy, the pressure on the pulp fiber during drying will be excessive, the pulp fiber may be discolored, the strength of the pulp fiber itself may be reduced, and if the density is too low The desired strength may not be obtained or the surface smoothness may be reduced.
[0038]
The material of the outer layer container 3 is not particularly limited as long as it is a pulp fiber, and may be wood pulp, non-wood pulp, a recycled product thereof, or a mixed product obtained by mixing these at a predetermined ratio. Examples of the pulp fibers constituting the outer layer container 5 include unbleached or bleached kraft pulp, sulfite pulp, alkali pulp, ground pulp, and thermomechanical pulp. Among these, bleached kraft pulp of conifers and hardwoods is particularly preferable from the viewpoints of moldability, whiteness, surface properties of the molded body, and strength. These fibers can be used alone or in admixture of two or more at an appropriate ratio.
[0039]
The outer layer container 3 may contain additives for outer layers such as a dispersant, a pigment, a fixing agent, an antifungal agent, a sizing agent, an adhesive, and a paper strength enhancer as necessary.
[0040]
Next, the manufacturing method of the pulp mold molding of this invention is demonstrated based on one Embodiment applied to manufacture of the said food container 1. FIG.
[0041]
In the manufacturing method of the food container 1 of this embodiment, the container-shaped papermaking body 2 ′ and the papermaking body 3 ′ for the inner layer container 2 and the outer layer container 3 are individually wet-paper-made, and these papermaking bodies are combined and dried. A two-layer container having an inner layer container 2 and an outer layer container 3 is formed by molding and integrating.
[0042]
As shown in FIGS. 2 (a) and 2 (b), the papermaking portions 120 and 130 are formed of a convex elastic body, and the papermaking portions are predetermined. The papermaking molds 12 and 13 covered with a synthetic resin net (not shown) having a mesh size and a wire diameter of 1 are used.
[0043]
As shown in FIG. 2A, the papermaking portion 120 of the papermaking mold 12 has a flange portion 121 and has a predetermined taper angle and tapers toward the tip portion. A fine papermaking portion 123 is further provided at the tip of the papermaking portion 120 through a step 122. The size and shape of the papermaking portion 120 including the fine papermaking portion 123 is the same as that of the male die 15 (see FIG. 2 (e)) for forming the papermaking body 2 'produced by the papermaking die 12 as described later. It is designed to be substantially equal to the size and shape of the molding part 150 of the male mold 15 when it is disposed and dried.
[0044]
The length of the fine paper-making part 123 is set to be longer than the length of the thin molding part 151 (see FIG. 2 (e)) of the male mold 15 before the elastic deformation. In the present embodiment, when considering the length of the finely formed portion 151 and the amount of elastic deformation of the finely formed portion 123 at the time of dehydration molding of the papermaking body 2 ′, the length L123 of the finely formed portion 123 is 21 to 30 mm, In particular, it is preferably 22 to 28 mm.
[0045]
When the papermaking mold 12 is combined with a later-described female mold 16 (see FIG. 2D), the outer peripheral surface of the convex portion of the papermaking section 120 and the inner circumference of the papermaking body 3 ′ are in a state before elastic deformation. A desired gap is formed between the surface and the surface, and the length of the convex portion is longer than the depth of the concave portion 160 of the female die 16. Thus, as will be described later, the papermaking mold 12 is combined with the female mold 16 (see FIG. 2 (d)), and the papermaking body 120 is elastically deformed while the papermaking body 2 'is placed in the female mold 16, thereby making the papermaking body. 2 'can be pressed against the inner surface of the recess 160 of the female mold 16 to dehydrate and form the papermaking body 2' in a desired shape, and the papermaking body 2 'can be combined with the papermaking body 3'. The papermaking body 2 ′ can be released from the papermaking mold 12 while remaining inside.
[0046]
A large number of gas-liquid flow passages 124 opened on the outer surface are provided inside the papermaking section 120. These gas-liquid flow passages 124 are densely (many) arranged in the fine papermaking unit 123. In the present embodiment, a gas-liquid flow passage that is about twice as large as the other parts of the papermaking unit 120 is opened in the fine papermaking unit 123. As a result, a large amount of solid content in the slurry is deposited on the portion of the net that covers the fine paper-making part 123, and the paper-making body 2 'is placed in the female die 16 and dehydrated (FIG. 2 (d)). Reference), a desired basis weight difference is obtained in the body portion 21 ′ of the papermaking body 2 ′. Further, since the fine papermaking portion 123 is provided to increase the amount of solid content in the slurry, there is no possibility that the papermaking body 2 ′ is damaged when inserted into the recess 160 of the female die 16.
[0047]
As shown in FIG. 2 (b), the papermaking portion 130 of the papermaking mold 13 has a flange portion 131 and has a predetermined taper angle and tapers toward the tip portion. A large number of gas-liquid flow passages 132 opened on the outer surface are provided inside the paper making section 130. A gas-liquid flow passage 132 is disposed substantially uniformly at a portion corresponding to the body portion 31 ′ of the papermaking body 3 ′ in the papermaking portion 130 so that the solid content in the slurry is deposited substantially uniformly. As a result, as described later, when the papermaking body 3 ′ is dehydrated and further dried, the body portion 31 ′ of the papermaking body 3 ′ is dewatered and molded with a substantially uniform basis weight.
[0048]
When the papermaking die 13 is combined with the female die 14 (see FIG. 2C), the outer peripheral surface of the convex portion of the papermaking portion 130 and the inner periphery of the concave portion 140 of the female die 14 in a state before elastic deformation. A desired gap is formed between the surface and the surface, and the length of the convex portion is longer than the depth of the concave portion 140 of the female mold 14. Thus, the papermaking mold 13 can be combined with the female mold 14, and the papermaking body 3 'can be pressed against the female mold 14 while the papermaking portion 130 is elastically deformed to dry-mold the papermaking body 3' in a desired shape. It is like that.
[0049]
It is preferable to use an elastic body such as silicone rubber as the material of the papermaking portions 120 and 130 in the papermaking molds 12 and 13 from the viewpoint of heat resistance and corrosion resistance.
[0050]
In this embodiment, before combining the papermaking body 2 ′ and the papermaking body 3 ′, the papermaking body 3 ′ is dehydrated and further dried. A female die 14 (see FIG. 2 (c)) is used for dehydration molding and dry molding of the papermaking body 3 '.
[0051]
The female die 14 is made of a metal such as aluminum having rigidity, and has a recess 140 corresponding to the outer shape of the outer layer container 3 (food container 1). A band heater 141 is disposed on the outer periphery of the female die 14. It is preferable to use a female die 14 that does not have an exhaust hole that opens on the inner surface of the recess 140 so as not to leave behind on the outer surface of the food container 1, but when it is desired to shorten the dry molding time. Can also have an exhaust hole.
[0052]
As a die for integrating the papermaking body 2 ′ and the papermaking body 3 ′ and dry-molding, a molding die having a male die 15 and a female die 16 for coalescence molding is used as shown in FIG. The male mold 15 and the female mold 16 are metal molds such as aluminum having rigidity.
[0053]
The male mold 15 has a convex molded portion 150 corresponding to the inner surface shape of the inner layer container 2. A thin molding portion 151 having a reduced diameter corresponding to the stacking step 22 of the inner layer container 2 is provided at the tip of the molding portion 150. A length L151 of the narrow forming portion 151 is provided to be equal to or shorter than a length L123 of the fine papermaking portion 123 of the papermaking mold 12. The minimum value of the length L151 of the thin molded portion 151 is set according to the thickness of the barrel portion of the container 1 and the angle of the barrel portion.
[0054]
In the present embodiment, the difference between the length of the thin molding portion 151 and the length of the fine papermaking portion 123 is preferably 9 mm or less, particularly 1 to 7 mm. If the difference is too small, the step forming position by the fine paper-making part 123 is too low, and it becomes difficult to form a sufficient stacking step in the thin forming part 151, and if it is too large, the high density part is unnecessarily increased in the thin part. .
[0055]
A plurality of gas-liquid flow passages (not shown) that open in the form of slits on the outer peripheral surface are provided inside the molding unit 150, and when the papermaking bodies 2 'and 3' are combined through these gas-liquid flow passages. Can be dehydrated and exhausted. Further, a cartridge heater (not shown) is disposed inside the molding unit 150 so that heating can be performed from the outer surface of the molding unit 150.
[0056]
The female mold 16 is made of a metal such as aluminum having rigidity, and has a recess 160 corresponding to the outer shape of the outer layer container 3 (food container 1). A band heater 161 is disposed on the outer periphery of the female die 16. The female die 16 is provided so that a predetermined clearance (cavity) corresponding to the stepped portion 22 is formed between the convex portion of the molding portion 150 and the concave portion 160 when combined with the male die 15. ing. It is preferable to use a female mold 16 that does not have an exhaust hole opened on the inner surface of the recess 160 so as not to leave behind on the outer surface of the food container 1, but when it is desired to shorten the dry molding time. Can also have an exhaust hole.
[0057]
When making the papermaking body 2 ′ and the papermaking body 3 ′, as shown in FIGS. 2A and 2B, the papermaking molds 12 and 13 are placed with the papermaking portions 120 and 130 facing upward. The outer frames 125 and 133 are combined so as to surround the papermaking portion. Then, a predetermined amount of raw material slurry is injected through injection nozzles 126 and 134 attached to the outer frames 125 and 133, and the slurry is sucked through the gas-liquid flow passages 124 and 132, so that the solid content in the raw material slurry is on the net. To deposit.
[0058]
It is preferable to use a slurry having a pulp fiber concentration of 0.1 to 2 wt% as a raw material slurry used for papermaking of the papermaking body 2 ′. Although there is no restriction | limiting in particular in a dispersion medium, It is preferable to use water or white water as a dispersion medium from the point of handleability and production cost. Moreover, the said additive for inner layers can be contained in a slurry in a suitable ratio as needed.
[0059]
As a raw material slurry used for papermaking of the papermaking body 3 ′, it is preferable to use a slurry having a pulp fiber concentration of 0.1 to 2 wt%. Although there is no restriction | limiting in particular in a dispersion medium, It is preferable to use water or white water as a dispersion medium from the point of handleability and production cost. In addition, the raw material slurry may contain the outer layer additive in an appropriate ratio, if necessary.
[0060]
The papermaking body 3 'is finished with a good outer surface and, in order to increase the strength, it is dehydrated in advance before being superposed on the papermaking body 2', dried and densified. Specifically, after the papermaking, the outer frame 133 is retracted from the papermaking mold 13 and abutted against the female mold 14 together with the papermaking body 3 'as shown in FIG. 2 (c). Then, the wet papermaking body 3 ′ is pressed by the papermaking section 130 of the papermaking mold 13 to perform dehydration molding. When the papermaking body 3 ′ is dehydrated, the liquid content of the papermaking body 3 ′ is sucked through the gas-liquid passage 132 of the papermaking mold 13 and discharged to the outside.
[0061]
After the papermaking body 3 ′ is dehydrated to a predetermined moisture content, the female mold 14 is heated to a predetermined temperature by the band heater 141, and dry-molded while pressing the papermaking body 3 ′ against the recess 140 by the papermaking section 130 of the papermaking mold 13. . And the papermaking body 3 'is dried and densified. When the papermaking body 3 ′ is dried, the liquid (vapor) of the papermaking body 3 ′ is sucked through the gas-liquid passage 132 of the papermaking mold 13 and discharged to the outside.
[0062]
The mold temperature (temperature of the female mold 14) at the time of drying the papermaking body 3 ′ is preferably 110 to 250 ° C., particularly 120 to 230 ° C. in terms of prevention of scorching due to drying, drying efficiency, and the like. After completion of drying, the papermaking mold 13 is retracted. At this time, the compressed air can be purged through the gas-liquid flow passage 132 in the paper making section 130 and quickly separated. After releasing from the papermaking mold 13, the papermaking body 3 ′ moves to the female mold 16 for coalescence molding.
[0063]
Next, as shown in FIG. 2 (d), the papermaking body 2 ′ is overlaid from below the papermaking body 3 ′ after dehydration and drying disposed in the female mold 16. At this time, the papermaking body 2 ′ is not removed from the papermaking mold 12, and the papermaking mold 12 is directly butted against the female mold 16. Then, the papermaking body 2 'in the wet state is pressed against the concave portion 160 by the papermaking section 120 of the papermaking mold 12, dewatering is performed while elastically deforming the papermaking section 120, and the papermaking body 3' is dehydrated and formed. 'Close contact with. The mold temperature (temperature of the female mold 16) at this time is preferably 150 to 250 ° C., particularly 170 to 230 ° C., from the viewpoint of drying efficiency and prevention of scorching.
[0064]
At this time, a load is applied to the papermaking mold 12 so that the height L22 ′ from the concave portion 160 to the step 22 ′ is higher than the height L22 from the concave portion 160 to the step 22 (see FIG. 2E). The part 120 is preferably elastically deformed. Thereby, the basis weight w of the part corresponding to the said vicinity part 23a in the said papermaking body 2 '(refer FIG.1 (b)). _23a And the basis weight w of the part corresponding to the said thick part 24 _{twenty four} Is the basis weight w of the portion corresponding to the other portion 23b. _23b The papermaking body 2 is dewatered and molded so as to be larger. Thus, the basis weight w _23a And basis weight w _{twenty four} Is the basis weight w _23b By performing dehydration molding so as to be larger than that, a molded body having a predetermined density in the body portion can be obtained in the dry molding using the male mold 15 and the female mold 16. Here, the basic weight of each part is calculated | required from the weight of the pulp cut out from the predetermined | prescribed site | part, and the cut-out area.
[0065]
Basis weight w of the portion corresponding to the vicinity 23a in the papermaking 2 ' _23a Is 75-2800 g / m ² , Especially 175-1500 g / m ² It is preferable that
[0066]
Basis weight w of the portion corresponding to the other portion 23b in the papermaking body 2 ′ _23b Is 25 to 2000 g / m ² , Especially 70-1200g / m ² It is preferable that
[0067]
Basis weight w of the portion corresponding to the thick portion 24 in the papermaking body 2 ′ _{twenty four} Is 50 to 3000 g / m ² Is preferably 210 to 1800 g / m. ² It is more preferable that
[0068]
After the papermaking body 2 ′ and the papermaking body 3 ′ are sufficiently adhered, the papermaking mold 12 is raised to separate the papermaking body 2 ′ from the papermaking mold. At this time, the compressed air can be purged through the gas-liquid flow passage 124 in the paper making unit 120 and quickly separated. The papermaking mold 12 from which the papermaking body 2 ′ is separated is retracted.
[0069]
Next, as shown in FIG. 2 (e), the male mold 15 is butted against the female mold 16, and the combined papermaking body 2 ′ and papermaking body 3 ′ are dry-molded.
[0070]
In the dry molding, the male mold 15 and the female mold 16 are heated to a predetermined temperature with respective heaters, and the papermaking body 2 ′ and the papermaking body 3 ′ are integrated with being pressed with a predetermined pressing force. Further, at the time of dry molding, the moisture of the papermaking body 2 ′ is discharged outside as steam through the gas-liquid flow passage of the male mold 15.
[0071]
Further, the flange portions 20 ′ and 30 ′ of the respective papermaking bodies 2 ′ and 3 ′ are joined and integrated by a pressing force during dry molding. An adhesive may be used for joining the flange portions 20 ′ and 30 ′ in terms of increasing the adhesive strength. In this case, it is particularly preferable to use an adhesive such as starch as a food container.
[0072]
The mold temperature (temperature of male mold 15 and female mold 16) at the time of dry molding is 150 to 250 from the viewpoint of preventing scorching from each papermaking body 2 ′ and 3 ′ and maintaining high drying efficiency. It is preferable that it is 170 degreeC, especially 170-230 degreeC.
[0073]
When the papermaking bodies 2 ′ and 3 ′ are dried to a predetermined moisture content and the papermaking body 2 ′ and the papermaking body 3 ′ are tightly integrated, the dry molding is finished. Then, the male mold 15 and the female mold 16 are separated from each other, and the molded body is removed. Then, if necessary, the obtained molded body is subjected to processing such as trimming to complete the manufacturing of the molded body.
[0074]
As described above, the food container 1 of the present embodiment has a density in the vicinity 23a of the thin portion 23 in the trunk portion of the inner layer container 2 that is higher than the density of the other portion 23b and the thick portion 24. Since a low density portion is not formed at the step, the stack step can have sufficient strength. Further, since the density of the vicinity of the stack step is high, the wear resistance is excellent when the bottom corner contacts the inner periphery of the lower container when the containers are stacked. It also has lightweight (thin, low density), moldability (especially transferability of stack steps and smoothness of inner and outer surfaces), heat insulation and strength, and the inner and outer layers are mainly composed of pulp. Also excellent in properties. Note that the step includes a case where the thickness changes continuously due to the taper and the thickness changes (stacking occurs at any part of the changed thickness).
[0075]
Moreover, according to the manufacturing method of the food container of this embodiment, the food container 1 which has the said effect can be manufactured suitably.
[0076]
The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.
[0077]
For example, a coating layer (not shown) may be provided with a resin film on the inner side of the inner layer container 2 or the outer side of the outer layer container 3 in the food container 1 of the embodiment.
Examples of the resin film used for the coating layer include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon, polyvinyl resins such as polyvinyl chloride, and styrene such as polystyrene. Examples include thermoplastic resin films such as polyethylene resins, biodegradable resin films such as modified polyethylene terephthalate, aliphatic polyester, etc. In terms of production cost, moldability, etc., polyolefin resins are preferred, and environmentally friendly disposal From this point, a biodegradable resin film is preferable. These resin films can be used alone or in a laminate of two or more for the coating layer. The coating layer can also be provided by applying a paint containing the resin component.
[0078]
There is no particular limitation on the papermaking method of each papermaking body, but for example, the papermaking mold can be immersed in a pool containing a predetermined raw material slurry and suction papermaking can be performed. The papermaking body 3 ′ can also be dried by the female mold 16 used when the papermaking bodies 2 ′ and 3 ′ are combined. Moreover, the direction of each mold at the time of molding is not limited to that of the above-described embodiment, and for example, it may be inverted up and down.
[0079]
In the present invention, as in the above-described embodiment, the thickness changes from the thin portion of the trunk portion to the thick portion through the stack step, and the density in the vicinity of the stack step in the thin portion is the other portion of the thin portion and Although it is suitable for manufacture of a food container higher than a thick part, it is applicable also to other pulp mold molded objects. For example, the present invention can also be applied to the manufacture of a pulp mold container or the like having a stepped line, a step for engraving or a pattern.
[0080]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Like the following Example, the food container (container with a flange) of the two-layer structure shown in FIG. 1 was produced. In the course of production, the basis weight of the inner layer container after dehydration molding is measured as follows, and the vicinity of the step for stacking in the thin part of the inner layer container after dry molding, the other part, and the thick part, respectively. The density of was measured. Further, the moldability, strength, and heat insulation properties of the obtained container were examined and evaluated as follows. The results are shown in Table 1.
[0081]
[Example 1]
<Dimension of inner layer container>
Height H: 110mm
Opening inner diameter φ1: 90mm
Bottom outer diameter φ2: 70mm
Upper part thickness T1: 1.5mm
Body center (thin wall) thickness T2: 1.7 mm
Lower trunk (thick part) thickness T3: 2.7 mm
Bottom thickness T4: 1.7mm
Flange thickness T5: 3mm
Stacking step: 1mm
[0082]
<Paper making for inner layer container>
Combine the outer frame with a papermaking mold equipped with a silicone rubber papermaking part and a nylon net (50 mesh, wire diameter 100 μm) covering the papermaking part, and inject slurry for the inner layer (raw material slurry) with the following composition. And the papermaking body for inner-layer containers was produced.
Dimensional shape of the papermaking part of the papermaking mold for the inner layer;
Length of fine paper making part L123: 27mm
Height L12 of the convex part of the papermaking part: 125mm
Step: 1mm
Taper angle: 10.5 degrees
Slurry for inner layer;
Pulp fiber: 50% by weight of bulky treated pulp (cross-linked pulp “HBAFF” manufactured by Warehauza, USA) + Senibra (LBKP) and Hinton (NBKB) mixed at a weight ratio of 70:30 to adjust the freeness to 400 ml 50 weight %
Binder: PVA, 1% by weight of pulp fiber
Sizing agent: “AS262” manufactured by Japan PMC, 2% by weight of pulp fiber
Dispersant: PEO, 0.1% by weight of pulp fiber
Pulp fiber concentration: 0.25% by weight
[0083]
<Making paper for outer layer container>
The outer frame is combined with a papermaking mold having a papermaking part made of silicone rubber having the following shape and a nylon net (50 mesh, wire diameter 100 μm) covering the papermaking part, and a slurry for the outer layer (raw material slurry) having the following composition is used as a nozzle. The papermaking body for the outer layer container was produced.
Dimensional shape of the papermaking part of the papermaking mold for the outer layer;
Height L13 of the convex part of the papermaking part: 125 mm
Taper angle: 10.9 degrees
Slurry for outer layer;
Pulp fiber: CENIBRA (LBKP): Hinton (NBKB) = 70:30 (weight ratio) adjusted to 400 ml freeness
Sizing agent: “AS262” manufactured by Japan PMC, 1% by weight of pulp fiber
Pulp fiber concentration: 0.25% by weight
[0084]
<Dehydration, dry molding, etc. of papermaking for outer layer container>
In addition, the papermaking for the outer layer container was placed in a female mold for dry molding having a recess substantially corresponding to the outer shape of the food container, dehydrated under the following conditions, and subsequently dry molded.
Mold temperature: 120 ° C
Press load: 6000 N (120 seconds)
[0085]
<Combination of each papermaking>
After overlapping each papermaking body in the female mold | die for coalescence shaping | molding which has the recessed part substantially corresponding to the external shape of a food container, both papermaking bodies were integrated on the following conditions.
Press load: 6000 N (1 second)
[0086]
<Dry molding of combined papermaking>
Both papermaking bodies were integrated under the following conditions using a molding die for coalescence molding composed of a male die having the following shape and the female die.
Dimensional shape of the molding part of the mold (male mold);
Molded part length L15: 108.3 mm
Thin molded part length L151: 21mm
Step: 1mm
Molded part taper angle: 7 degrees
Mold temperature: 200 ℃
Press load: 9800 N (90 seconds with the male flange part butted against the female opening perimeter through the flange part of the molded body)
[0087]
[Comparative Example 1]
A papermaking mold similar to the papermaking mold for the inner layer used in Example 1 was used in the same manner as in Example 1 except that it did not have a fine papermaking part and had a tapered shape as it was.
[0088]
[Comparative Example 2]
Except that the paper-molded molded body for the inner layer was dewatered and molded so that the basis weight of the thin part other than the vicinity of the stepped part was increased, and the thin part and the thick part were formed through the stacking step with the mold. It was produced in the same manner as the example.
[0089]
[Measurement of basis weight of inner layer container]
It calculated from the weight and area of the inner layer container cut out from the predetermined part.
[0090]
[Evaluation of formability]
The inner surface of the produced container was observed with the naked eye, and the state of wrinkles and fractures was examined and evaluated in the following three stages.
○: Wrinkle, no break
×: There is a break in the stack step.
[0091]
[Evaluation of strength]
The produced containers were stacked with a load of 4 kgf, the state of the stacking step was examined, and the following three stages were evaluated.
○: Less bite of the container. Detachment after stacking is no problem and stack collapse does not occur.
X: The bite of the container is large. Separation after stacking is not easy, and the stack may collapse.
[0092]
[Evaluation of thermal insulation]
Hot water at 100 ° C. was poured into the prepared container, poured into the tip, and after 3 minutes, it was examined whether the body could be grasped with bare hands and evaluated in the following three stages.
○: Thickness that can be held by hand.
X: Hot enough to hold by hand, or hot enough to hold by hand.
[0093]
[Table 1]

[0094]
As shown in Table 1, the container of Example 1 is excellent in all of formability, heat insulation, and strength, whereas in Comparative Example 1, the papermaking mold is a female mold for coalescence molding after the inner layer is made. When the abutment was brought into contact with the inner surface of the female mold, the swell of the pulp at the tip of the papermaking body was brought into contact with the inner surface of the female mold. Moreover, when the density of the vicinity of the step, the density of the thick part, and the density of the thick part were made smaller than those of other parts, blocking occurred when stacked. Further, when the film was laminated by vacuum forming, cracks occurred in the stack portion.
[0095]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and pulp mold shaping | molding container of a pulp mold molded object which are lightweight, excellent in a moldability and heat insulation, have high intensity | strength, and are excellent also in discardability are provided.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing an embodiment in which a pulp molded container of the present invention is applied to a food container, where (a) is a half sectional view and (b) is an enlarged view of the main part of (a). It is.
FIG. 2 is a diagram schematically showing a process of an embodiment in which the method for producing a pulp mold product of the present invention is applied to the production of a food container, and (a) shows the paper making process of the paper product for the inner layer container. Figure, (b) is a diagram showing the paper making process of the outer container container, (c) is a diagram showing the dehydration / dry molding process of the outer container paper, (d) the inner container paper and the outer container The figure which shows the coalescing process of a papermaking body, (e) is a figure which shows the dry molding process of a food container.
[Explanation of symbols]
1 Food container
2 Inner layer container (pulp molding container)
20 Flange
21 Torso
22 Steps for stacking (steps)
23 Thin section
23a Neighborhood
24b Other parts
24 Thick part
3 Outer container
30 Flange
31 Torso
2 ', 3' papermaking
12, 13 Papermaking mold
120, 130 Papermaking department
123 Fine paper making section
14 Female
140 recess
15 Male
150 Molding part
151 Thin molding part
16 female
160 recess

Claims (7)

The thickness changes from the thin part to the thick part through the step, and the density of the vicinity of the step in the thin part is higher than the density of the other part of the vicinity in the thin part and the thickness A method for producing a pulp mold molded body having a density equal to or higher than a density of a part,
The papermaking body is dehydrated and molded so that the basis weight of the portion corresponding to the thick portion and the vicinity of the step in the thin portion is higher than the basis weight of the portion corresponding to the other portion of the thin portion, A method for producing a pulp mold molding, wherein the papermaking body is dry-molded while being pressed in a mold having a cavity corresponding to the step. The method for producing a pulp mold product according to claim 1, wherein the papermaking product is made from a slurry containing bulky treated pulp. The method for producing a pulp molded article according to claim 1, wherein the papermaking product is made from a slurry containing a bulking agent. The papermaking part of the papermaking mold is formed with a convex elastic body so as to make the papermaking body into a container shape, and a fine papermaking part is provided on the outer peripheral surface of the papermaking part that becomes thinner corresponding to the difference in basis weight. ,
The molding die is composed of a rigid male die having a thin molding portion at the tip that narrows corresponding to the step and a rigid female die combined with a clearance between the male die and the thin die. The molding part is provided shorter than the length of the fine papermaking part,
When the papermaking body is placed in the mold, the papermaking body is pressed against the inner surface of the female mold while elastically deforming the papermaking portion, and the papermaking body is dehydrated and molded. The method for producing a pulp molded article according to any one of claims 1 to 3, wherein the molding is performed by pressing with a rigid male mold in a mold. The pulp mold molded body according to any one of claims 1 to 4, wherein a papermaking body different from the papermaking body is disposed in the mold before the papermaking body is disposed in the mold. Method. The method for producing a pulp mold molded body according to claim 5, wherein the other papermaking body is dried in advance before being placed in the mold. The thickness changes from the thin part to the thick part through the stacking step, and the density of the vicinity of the step in the thin part is higher than the density of the other part in the vicinity of the thin part, and Pulp molded container that is greater than the density of the thick part.

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